Pros and Cons of nonvented boilers

Because he can charge you more perhaps ?

Ask him why he hasn't recommended a heat store instead.

Or even a more efficient condenser boiler.

Easier to fill and flush Less chance of air locks No danger of pumping over No evaporation - so no oxygen-laden replacement water being introduced (assuming there are no leaks) No header tank to worry about, or ball valve to stick Less draining required (or spillage potential) when working on the system

Cons: Slightly more prone to leak - especially old radiator valves More difficult to introduce inhibitor Need to keep an eye on the pressure gauge, and top up if necessary

I'm sure there are others, but that will do for starters. I'm considering converting my vented system to non-vented because I believe that, on balance, the pros outweigh the cons. My boiler is happy with either.

Er no, that's not it.

The question is about a non-vented vs. vented *boiler* meaning the primary circuit.

A heat store is all about how the domestic hot water is done - i.e. a pressurised cylinder where the bulk of the water is that that will be used at the taps directly, vs. it being used, typically vented in a heat store to store the energy to heat the DHW via a separate heat exchanger.

Whether or not the primary circuit through the boiler is vented is a separate issue.

A search on Google Groups for posts by Ed Sirett will give the URL for a good FAQ on sealed primary systems.

.andy

To email, substitute .nospam with .gl

See FAQ (sealedCH) below.

If you're talking about the primary circuit being sealed and pressurised.

Pros: Everything. Cons: Nothing.

Well, maybe it isn't quite so simple, but it is close enough for government work.

Christian.

It is sealed, so little chance of oxygenation. No F&E tank used

Nothing? Blow-off pipe through a wall. Expansion vessel to fail. A small weep leak is not tolerated as the pressure will drop (some boilers cut out at low pressure).

The simplest, and most reliable, is an open vented system. But the F&E tanks take up space and extra pipes to it. As long as the correct , and enough, inhibitor is used and changed at regular intervals there should be not problems.